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HTML 

              
                <div class="wrapper dark">
	<div class="darkmode">
		<h1 class="headline">Image Compare</h1>
		<div id="toggle-darkmode"><i class="fa-solid fa-circle-half-stroke"></i></div>
	</div>
	<div id="image-container" class="image-container">
		<div class="image original"></div>
		<div class="image draft"></div>
		<div id="slider"></div>
		<div class="err">
			<div class="err-msg">Select a valid Image Source</div>
		</div>
		<div class="flag"><span><i class="fi fi-ua"></i>Slava Ukraini!</span></div>
	</div>
	<div class="settings">
		<div class="image-urls">
			<h2 class="headline"><i class="fa-solid fa-image"></i>Image URLs:</h2>
			<div class="input-urls">
				<div class="input-url filter">
					<label>Image URL:<span>Filter</span></label>
					<input id="img-filter" type="url" value="" placeholder="https://your-image-path" />
				</div>
				<div class="input-url original">
					<label>Image URL:<span>Original</span></label>
					<input id="img-original" type="url" value="" placeholder="https://your-image-path" />
				</div>
			</div>
		</div>
		<div class="filter-container">
			<h2 class="headline"><i class="fa-solid fa-filter"></i>Filters:</h2>
			<label class="filter-label">
				<input id="grayscale" class="filter" type="radio" value="grayscale" name="filter" checked />
				Grayscale
			</label>
			<label class="filter-label">
				<input id="blur" class="filter" type="radio" value="blur" name="filter" />
				Blur
			</label>
			<label class="filter-label">
				<input id="sepia" class="filter" type="radio" value="sepia" name="filter" />
				Sepia
			</label>
			<label class="filter-label">
				<input id="none" class="filter" type="radio" value="none" name="filter" />
				None
			</label>
		</div>
	</div>
!

CSS 

              
                * {
	margin: 0;
	padding: 0;
	font-family: "Open Sans", sans-serif;
	box-sizing: border-box;
	transition: color ease-in-out 0.36s;
}
body {
	background-color: #fafafb;
	&.dark {
		background-color: rgba(0, 0, 0, 1);
		.wrapper {
			.darkmode {
				h1.headline {
					color: rgba(255, 255, 255, 1);
				}
				#toggle-darkmode {
					color: rgba(255, 255, 255, 1);
				}
			}
		}
		#image-container {
			border-color: rgba(0, 0, 0, 1);
			#slider {
				background-color: rgba(255, 255, 255, 1);
			}
		}
		.settings {
			background-color: rgba(255, 255, 255, 0.1);
			h2.headline {
				color: rgba(255, 255, 255, 1);
			}
			.input-urls {
				.input-url {
					label {
						color: rgba(255, 255, 255, 1);
					}
				}
			}
			.filter-container {
				.filter-label {
					color: rgba(255, 255, 255, 1);
				}
			}
		}
	}
}
.wrapper {
	width: 640px;
	margin: 46px auto;
	display: flex;
	justify-content: center;
	flex-direction: column;
	align-content: center;
	align-items: center;
	.darkmode {
		width: 100%;
		display: flex;
		h1.headline {
			font-size: 16px;
			letter-spacing: 0.5px;
			margin-bottom: 16px;
			text-transform: uppercase;
			flex-grow: 1;
			color: rgba(0, 0, 0, 0.84);
		}
		#toggle-darkmode {
			color: rgba(0, 0, 0, 0.84);
			cursor: pointer;
		}
	}
	#image-container {
		width: 640px;
		height: 358px;
		background-color: #fafafb;
		border: 1px solid #f1f1f2;
		border-radius: 6px;
		position: relative;
		overflow: hidden;
		.image {
			width: 640px;
			height: 358px;
			position: absolute;
			top: 0;
			left: 0;
			background-size: cover;
			background-position: top left;
			background-repeat: no-repeat;
			background-color: #ff7979;
		}
		#slider {
			width: 5px;
			height: 100%;
			background-color: rgb(0, 0, 0);
			cursor: w-resize;
			position: absolute;
		}
		.err {
			width: 100%;
			height: 100%;
			display: none;
			flex-align: column;
			align-items: center;
			justify-content: center;
			position: absolute;
			top: 0;
			left: 0;
			background: #ff7979;
			&.fadeIn {
				animation-name: fadeIn;
				-webkit-animation-name: fadeIn;
				animation-duration: 0.36s;
				-webkit-animation-duration: 0.36s;
				animation-timing-function: ease-in-out;
				-webkit-animation-timing-function: ease-in-out;
				display: flex;
			}
			.err-msg {
				font-size: 24px;
				color: #fff;
			}
		}
		.flag {
			width: 200px;
			display: flex;
			position: absolute;
			bottom: 16px;
			left: 16px;
			text-shadow: 0px 0px 2px #000000;
			span {
				color: #fff;
				i {
					margin-right: 8px;
				}
			}
		}
	}
	.settings {
		width: 100%;
		display: flex;
		flex: 1 1 0;
		margin: 16px auto 0;
		background-color: rgba(255, 255, 255, 1);
		border-radius: 6px;
		h2.headline {
			width: 100%;
			font-size: 16px;
			letter-spacing: 0.3px;
			margin-bottom: 16px;
			padding-bottom: 8px;
			text-transform: capitalize;
			color: rgba(0, 0, 0, 0.84);
			border-bottom: 1px solid #f1f1f2;
			i {
				margin-right: 8px;
			}
		}
		.image-urls {
			flex-grow: 1;
			flex-basis: 0;
			padding: 16px;
			.input-urls {
				.input-url {
					label {
						display: flex;
						font-size: 16px;
						align-items: center;
						flex-grow: 1;
						span {
							margin-left: auto;
							font-size: 10px;
							text-transform: uppercase;
							color: rgba(0, 0, 0, 0.8);
						}
					}
					input {
						width: 100%;
						margin-top: 8px;
						padding: 8px 12px;
						border: none;
						background-color: #f1f1f2;
						border-radius: 3px;
						&::placeholder {
							color: rgba(0, 0, 0, 0.45);
						}
					}
					&.original {
						margin-top: 16px;
					}
				}
				display: flex;
				flex-direction: column;
			}
		}
		.filter-container {
			display: flex;
			flex-grow: 1;
			flex-basis: 0;
			flex-direction: column;
			justify-content: flex-start;
			align-content: flex-start;
			align-items: flex-start;
			align-self: flex-start;
			padding: 16px;
			.filter-label {
				display: flex;
				margin-bottom: 8px;
				cursor: pointer;
				font-size: 16px;
				letter-spacing: 0.3px;
				color: rgba(0, 0, 0, 0.84);
				.filter {
					margin-right: 8px;
				}
			}
		}
	}
}

// Animations
@keyframes fadeIn {
	0% {
		transform: scale(0);
		opacity: 0;
	}
	100% {
		transform: scale(1);
		opacity: 1;
	}
}

@-webkit-keyframes fadeIn {
	0% {
		-webkit-transform: scale(0);
		opacity: 0;
	}
	100% {
		-webkit-transform: scale(1);
		opacity: 1;
	}
}
!

JS 

              
                const imageCompare = function () {
	const imageContainer = document.getElementById("image-container");
	const canvas = imageContainer.getBoundingClientRect();
	const canvasSize = canvas.width;
	const imageOriginal = document.querySelector(".image.original");
	const imageDraft = document.querySelector(".image.draft");
	const imgSrcOriginal = document.getElementById("img-original");
	const imgSrcDraft = document.getElementById("img-filter");
	const darkMode = document.getElementById("toggle-darkmode");
	const filters = document.querySelectorAll(".filter");
	var isDark = false;

	// Image URLs
	const setImageSrc = function (src1, src2) {
		imgSrcOriginal.value = src1;
		imgSrcDraft.value = src2;

		// Change Image Source
		const changeImgSrc = function (el, src) {
			el.style.backgroundImage = `url("${src.value}")`;
		};

		// Set default img src for bg
		changeImgSrc(imageOriginal, imgSrcOriginal);
		changeImgSrc(imageDraft, imgSrcDraft);

		imgSrcOriginal.addEventListener("input", function () {
			changeImgSrc(imageOriginal, imgSrcOriginal);
		});

		imgSrcDraft.addEventListener("input", function () {
			changeImgSrc(imageDraft, imgSrcDraft);
		});
	};

	// Test URL: https://tinyurl.com/2s3dxphx
	// setImageSrc("https://tinyurl.com/ycksc32p", "https://tinyurl.com/ycksc32p");
	setImageSrc(
		"https://c4.wallpaperflare.com/wallpaper/506/679/697/city-futuristic-digital-art-cheng-yu-wallpaper-preview.jpg",
		"https://c4.wallpaperflare.com/wallpaper/506/679/697/city-futuristic-digital-art-cheng-yu-wallpaper-preview.jpg"
	);

	function dragElement(elmnt) {
		var pos1 = 0,
			pos2 = 0;
		elmnt.style.left = canvasSize / 2 + "px";
		imageDraft.style.width = elmnt.offsetLeft - pos1 + "px";
		if (document.getElementById(elmnt.id)) {
			/* if present, the header is where you move the DIV from:*/
			document.getElementById(elmnt.id).onmousedown = dragMouseDown;
		} else {
			/* otherwise, move the DIV from anywhere inside the DIV:*/
			elmnt.onmousedown = dragMouseDown;
		}

		function dragMouseDown(e) {
			e = e || window.event;
			e.preventDefault();
			// get the mouse cursor position at startup:
			pos2 = e.clientX;

			// pos4 = e.clientY;
			document.onmouseup = closeDragElement;
			// call a function whenever the cursor moves:
			document.onmousemove = elementDrag;
		}

		function elementDrag(e) {
			e = e || window.event;
			e.preventDefault();
			// calculate the new cursor position:
			pos1 = pos2 - e.clientX;
			pos2 = e.clientX;
			if (
				elmnt.offsetLeft - pos1 + 5 >= canvasSize ||
				elmnt.offsetLeft - pos1 + 5 <= 0
			) {
				elmnt.style.left = canvasSize - elmnt.width + "px";
			} else {
				// set the element's new position:
				elmnt.style.left = elmnt.offsetLeft - pos1 + "px";
				imageDraft.style.width = elmnt.offsetLeft + "px";
			}
		}

		function closeDragElement() {
			/* stop moving when mouse button is released:*/
			document.onmouseup = null;
			document.onmousemove = null;
		}
	}

	dragElement(document.getElementById("slider"));

	const setFilters = function () {
		let applyFilter = function (elm, fil) {
			elm.style.filter = fil;
		};
		filters.forEach((filter) => {
			filter.addEventListener("change", function () {
				switch (filter.value) {
					case "grayscale":
						imageDraft.style.filter = applyFilter(imageDraft, "grayscale(100%)");
						break;
					case "blur":
						imageDraft.style.filter = applyFilter(imageDraft, "blur(3px)");
						break;
					case "sepia":
						imageDraft.style.filter = applyFilter(imageDraft, "sepia(1)");
						break;
					case "none":
						imageDraft.style.filter = applyFilter(imageDraft, "none");
						break;
				}
			});
			// Set defauult Filter
			applyFilter(imageDraft, "grayscale(100%)")
		});
		
	};
	setFilters();

	const setMode = function () {
		darkMode.addEventListener("click", function () {
			isDark = !isDark;
			isDark
				? document.body.classList.add("dark")
				: document.body.classList.remove("dark");
		});
	};
	setMode();
};
imageCompare();
!
999px

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